/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.library.string;

import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;

/**
 * This function splits string from an input series according to given regex.
 */
public class UDTFRegexSplit implements UDTF {

    private String regex;
    private int index;

    @Override
    public void beforeStart(UDFParameters udfParameters, UDTFConfigurations udtfConfigurations)
            throws Exception {
        regex = udfParameters.getString("regex");
        index = udfParameters.getIntOrDefault("index", -1);
        udtfConfigurations.setAccessStrategy(new RowByRowAccessStrategy());
        if (index == -1) {
            udtfConfigurations.setOutputDataType(Type.INT32);
        } else {
            udtfConfigurations.setOutputDataType(Type.TEXT);
        }
    }

    @Override
    public void transform(Row row, PointCollector collector) throws Exception {
        String[] splitResult = row.getString(0).split(regex);
        if (index == -1) {
            collector.putInt(row.getTime(), splitResult.length);
        } else {
            if (index < splitResult.length) {
                collector.putString(row.getTime(), splitResult[index]);
            }
        }
    }

    @Override
    public void validate(UDFParameterValidator validator) throws Exception {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.TEXT)
                .validate(
                        regex -> ((String) regex).length() > 0,
                        "regexp has to be a valid regular expression.",
                        validator.getParameters().getStringOrDefault("regex", ""))
                .validate(
                        index -> (int) index >= -1,
                        "index must a non-negative integer to fetch split results or -1 to get length.",
                        validator.getParameters().getIntOrDefault("index", -1));
    }
}
